78 blazer rearend not the same..

[LS6 XAA]

Oddly enough, I measured everything on the front diff and it all appears to be identical to the original, springs are in the same places, same shock mounts etc....but I'll probably install the front diff at a later date when I have more time for a front end alignment.

I read just what u explained about the front axle for dana 44. corp 10 bolt may be same to ? any one... thanks for this great info and pics maybe some one can post a pic or video diy step by step on the rear end mod's
Firebirdjones : can u explain how u setup the relocation angle for the perchs, I never did the mod my self as far as the cutting off and moving, the po did it on the axle I removed and the donor axle had had this mod done to it all ready. my donor had a 4" susp lift & one perch broke of when I pulled it so I re welded it back on to match the other perch using a bubble level. I read to use a angle finder but decided to do it my way lol

[Firebirdjones]

I probably didn't explain that very clearly, as I had to read it again myself a couple of times

On the rearend, the spring perches on the 78 rearend are moved outward (toward the backing plates), about 1 1/2 inches,,,or about half of the spring perch width as you mentioned. So I moved them inward

I'm sure GM did this for more rear stability, just not sure when that change was made. I would assume with the square body change in 73....

I used an angle finder to reweld the perches at the same angle I removed them from. I compared that to the original 72 rearend in my blazer and they are setup at the same angle, so all driveline angles are unchanged.

Really very simple to do, just a little extra work that I wasn't expecting.

The front dana 44 diff from the 78 measures exactly the same as the dana 44 currently in my 72 blazer. So apparently GM didn't make any changes up there. That will be a simple swap with basic hand tools, but it will require a front end alignment when I'm done. So for right now I haven't tackled that until a make an appointment for the alignment rack.

[Blazed72]

What do you have to get an alignment for? Are they just checking the toe in/toe out?

[Firebirdjones]

Yeah basically. This other front diff I have sitting here is brand new with ball joints, tie rods, u-joints, rotors, calipers etc....

Basically a complete new front suspension ( but with my old springs). So just to be sure everything is set where it should be, I'll bolt it all in and take it to the alignment rack first thing. Make sure I don't ruin a $500 set of tires.

[Blazed72]

Gotcha, Didnt know if you were checking caster. Have you ever set the toe at home? Its pretty easy and you dont have to pay someone.

[Firebirdjones]

Yeah I use a little bubble gauge that attaches to the spindles to set both caster/camber and toe. But I only do that on my sandrail where precision isn't important.

For my daily driver I prefer to use real gauges and make sure it's set perfectly. Sometimes you get wierd vibrations in these 4x4's if alignments aren't near perfect.

They'll be checking caster/camber and toe on the blazer. Can't remember if you can change the camber or the caster at the spindle, it's been so long since I've messed with these, but we did change that stuff on jeeps we had. So I'll have it all looked at on the rack for piece of mind.

[cleszkie]

I'm not knocking the good job you did modifying the rear axle. But I'm just curious why you would go through the trouble to hang a 1/2 ton corporate 12 bolt under the rear with all that horsepower? Don't those have a tendancy to shear pinion gears under high load? Seems to me that a Dana 60 or 14 bolt would have been a better choice. Again, if you got a great deal on the 12 bolt, then I can see using it, but you may need to eventually upgrade if it grenades.